Capacitor dielectric having perovskite-type crystalline structure

ABSTRACT

A capacitor construction includes an inner electrode, an inner dielectric layer over the inner electrode, an outer dielectric layer over the inner dielectric layer, and an outer electrode over the outer dielectric layer. The inner dielectric layer can include an oxidized alloy of at least two metals in a perovskite-type crystalline structure. The outer dielectric layer can include an oxide of a material wherein the material exhibits passivation against carbon and nitrogen reaction. As an example, the capacitor construction can further include a middle dielectric layer between the inner and outer dielectric layers. The middle dielectric layer can include an oxidized alloy of at least two metals in a perovskite-type crystalline structure.

RELATED PATENT DATA

This patent resulted from a divisional application of U.S. patentapplication Ser. No. 09/945,137, filed on Aug. 30, 2001.

TECHNICAL FIELD

The invention pertains to methods of forming materials having aperovskite-type crystalline structure, methods of forming capacitordielectrics, capacitor dielectrics produced thereby, and capacitorconstructions.

BACKGROUND OF THE INVENTION

An increasing need exists for reducing the size and increasing theperformance of integrated circuit components, for example, dynamicrandom access memory (DRAM) and non-volatile field effect transistor(FET) memory, as well as other devices. One often common part ofintegrated circuit components includes dielectric material. Typically,using a dielectric material having a higher dielectric constant K in acapacitor allows storage of the same amount of electrical charge for agiven thickness of dielectric with a reduced capacitor area. Theincreased capacity to store electrical charge provides for fabricationof more advanced transistors. Further, substitution of higher Kdielectric can provide improved performance characteristics for a givendevice. Accordingly, a desire exists to produce higher K materials.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a method includes forming amaterial over a substrate, oxidizing the material, and, separately fromthe oxidizing, converting at least a portion of the oxidized material toa perovskite-type crystalline structure. As an example, the material caninclude an alloy of at least two metals. The oxidizing can includeexposure to an oxygen plasma and implanting oxygen ions into thematerial. The converting can include heating the oxidized material andreaching a maximum temperature no more than about one-half of a meltingpoint temperature of the perovskite-type material. The method canfurther include forming a passivation layer to carbon and nitrogen overthe material.

Another aspect of the invention includes forming an alloy materialcontaining at least two metals over a substrate, retardinginterdiffusion of the at least two metals, oxidizing the alloy materialafter retarding interdiffusion, and converting at least a portion of theoxidized alloy material to a perovskite-type crystalline structure. Asan example, retarding interdiffusion can include oxidizing at least anouter portion of the alloy material and implanting ions into the outerportion. Also, oxidizing the outer portion and implanting can occur insitu with forming the alloy material. The substrate can include acapacitor electrode and the converted, oxidized alloy material caninclude a capacitor dielectric layer.

In a further aspect of the invention, a capacitor dielectric formingmethod includes forming an alloy layer comprising at least two metalsover a capacitor, electrode, oxidizing the alloy layer, and convertingthe alloy layer to form a perovskite-type crystalline structure. As anexample, at least two of the metals can exhibit a substantial differencein chemical affinity for oxygen. Also, an additional alloy layer can befurther converted to an additional capacitor dielectric layer includinga perovskite-type crystalline structure.

In a still further aspect of the invention, a capacitor constructionincludes an inner electrode, an inner dielectric layer over the innerelectrode, an outer dielectric layer over the inner dielectric layer,and an outer electrode over the outer dielectric layer. The innerdielectric layer can include an oxidized alloy of at least two metals ina perovskite-type crystalline structure. The outer dielectric layer caninclude an oxide of a material wherein the material exhibits passivationagainst carbon and nitrogen reaction. As an example, the capacitorconstruction can further include a middle dielectric layer between theinner and outer dielectric layers. The middle dielectric layer caninclude an oxidized alloy of at least two metals in a perovskite-typecrystalline structure.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 shows a cross sectional view of a substrate fragment at aprocessing step according to an aspect of the invention.

FIG. 2 shows the substrate fragment of FIG. 1 at a processing stepsubsequent to that shown in FIG. 1.

FIG. 3 shows the substrate fragment of FIG. 2 at a processing stepsubsequent to that shown in FIG. 2.

FIG. 4 shows the substrate fragment of FIG. 3 at a processing stepsubsequent to that shown in FIG. 3.

FIG. 5 shows the substrate fragment of FIG. 2 at a processing stepsubsequent to that shown in FIG. 2 according to an alternative aspect ofthe invention.

FIG. 6 shows the substrate fragment of FIG. 5 at a processing stepsubsequent to that shown in FIG. 5.

FIG. 7 shows the substrate fragment of FIG. 6 at a processing stepsubsequent to that shown in FIG. 6.

FIG. 8 shows a cross sectional view of a substrate fragment according toan alternative aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

Perovskite-type materials are a class of crystalline, ceramic materialsincluding metal oxides. They exhibit a wide range of chemical andphysical properties and are accordingly of use in a variety ofapplications. For purposes of interpreting this disclosure and theclaims that follow, a “perovskite-type material” is defined as anymaterial substantially having a perovskite-type crystal structure,including perovskite itself (CaTiO₃), and other materials. The crystalstructure is referred to as “substantially” a perovskite-type crystalstructure to indicate that there can be distortions of the structurecorresponding to a theoretically ideal perovskite-type crystal structurein many of the materials having perovskite-type crystal structures,including, for example perovskite itself.

One use for perovskite-type material is as a dielectric. However, thevarious aspects of the invention herein are not limited to dielectrics.Other uses for the perovskite-type materials and methods of formationdescribed herein include gas permeable membranes, pressure sensors,solid oxide fuel cells, solid electrolytes, magnetic storage devices,etc. In a paraelectric crystal structure, perovskite-type materials canhave a dielectric constant (K) greater than 200, for example,Ba_(x)Sr_(1-x)TiO₃, and can be very useful for dynamic random accessmemory (DRAM). In a ferroelectric crystal structure, perovskite-typematerial can have K greater than 1000, for example, PbTiO₃, PbZrO₃,PbZr_(y)Ti_(1-y)O₃, and SrBi₂Ta₂O₉, and may be useful for non-volatilefield effect transistor (FET) memory.

According to one aspect of the invention, a method includes forming amaterial over a substrate, oxidizing the material, and converting atleast a portion of the oxidized material to a perovskite-typecrystalline structure. The material can have a composition which, whenfully oxidized, provides the composition of a perovskite-type materialthat can be converted to the perovskite-type crystalline structure.Forming the material can include depositing the material in a vacuumchamber at less than atmospheric pressure. Other methods known to thoseskilled in the art may also be suitable.

A variety of methods have been attempted for forming perovskite-typematerials. Oxidation of multi-layered pure metal (e.g., Nb/Ta) can beused to form multi-layered dielectric oxides. However, such methods havenot been used as precursor steps to producing a perovskite-typematerial. The oxidation process is facilitated by the similarity of themetals converted to oxides. Oxidation of metal films to formperovskite-type material is more complex both thermodynamically andkinetically. A metal alloy can be oxidized to form a perovskite-typecomposition. Additional processing allows formation of the desiredcrystal structure. Merely oxidizing the alloy produces an amorphousstructure of limited technological value given the much lower dielectricconstant compared to a perovskite-type crystalline structure.

One difficulty in forming perovskite-type material is that at least twoof the metals in a material to be converted can exhibit a substantialdifference in chemical affinity for oxygen. A difference in chemicalaffinity can result in preferential oxidation of one metal in comparisonto another metal. Diffusion of one of the metals in the material oftenenables the preferential oxidation. Accordingly, a material beginning asan alloy of at least two metals subject to preferential oxidation andrelated diffusion can acquire a morphology difficult to convert to aperovskite-type crystalline structure.

Differences in chemical affinities can be very large, as typified by theperovskite-type material PbTiO₃. Pb is a relatively inert metal withlimited affinity for oxygen. Ti is highly reactive and has an affinityfor oxygen exceeding that of Pb by many tens of orders of magnitude. Inthe context of the present document, “substantial difference” inchemical affinity refers to a difference sufficient to producepreferential oxidation of components in a material, such as an alloy,and/or interdiffusion of components in the material.

Perovskite-type material can also contain metals that exhibit asubstantial difference in chemical affinity for other non-metals,especially nitrogen and carbon. Reaction with nitrogen and carbon canform impurities difficult to remove from a material intended forperovskite-type crystalline structure and impact physical and chemicalcharacteristics potentially available in more pure perovskite-typematerial. Reaction with nitrogen and carbon can also produce diffusionin manner similar to that described for oxidation. As an example, Pbdoes not form stable nitrides or carbides, but Ti forms exceedinglystable nitrides and carbides. Cu, Ni, and Co can be found in someperovskite-type material and have limited affinities for oxygen andrelatively no affinity for nitrogen and carbon. Transition elements suchas Zr, Fe, Mn, Cr, V, and Ta can be present in perovskite-type materialand are more reactive with nitrogen and carbon. Alkaline earth metalsand lanthanide metals can be frequently found in perovskite-typematerial and are extremely reactive with oxygen, nitrogen, and carbon.

Perovskite-type material can contain metals that do not exhibit asubstantial difference in chemical affinities. For example, SrBi₂Ta₂ maybe oxidized to form a perovskite-type composition and the elements aresimilar in their reactivities with oxygen. Yet, a desire may exist toretard diffusion of elements in the alloy that could create difficultyin conversion to a perovskite-type crystalline structure. Accordingly,the aspects of the present invention can be advantageous even when nosubstantial difference exists in chemical affinity.

One method of forming a perovskite-type material includes forming amaterial over a substrate and heating the material in an oxidizingatmosphere, thereby simultaneously oxidizing and crystallizing thematerial into a perovskite-type material. However, as discussed above,preferential oxidation and/or diffusion of metals in the material mightinterfere with formation of perovskite-type crystalline structure.Accordingly, one aspect of the invention can include oxidizing thematerial and, separately from the oxidizing, converting at least aportion of the oxidized material to a perovskite-type crystallinestructure. Oxidizing the material separately from conversion to acrystalline structure allows for retarding interdiffusion of metals inthe material.

A variety of methods can be effective in retarding interdiffusion. Oneexample includes oxidizing at least an outer portion of material. In analloy material including at least two metals, oxidizing at least anouter portion of the alloy material can be used to decorate grainboundaries in the alloy with oxygen. The greater strength ofmetal-oxygen bonds relative to metal-metal bonds is known to producelarge increases in melting points of some metals upon oxidizing suchmetals. For similar reasons, oxidizing at least an outer portion of amaterial can be used to retard interdiffusion of the metals in thematerial. Implanting oxygen ions into an outer portion of the materialcan also be used alone or in combination with the described oxidizing toretard interdiffusion.

One example of oxidizing the outer portion includes exposure to anoxygen plasma. Implanting of oxygen ions can occur simultaneous with theexposure to the oxygen plasma. An oxygen plasma can contain a number ofspecies including neutral oxygen atoms as well and singly- anddoubly-charged ions and molecules. The relative concentrations of suchspecies can be varied over wide ranges by changing the plasma-generatingconditions, geometry and grounding of a plasma processing chamber. Usingthe knowledge of those skilled in the art, process parameters can beadjusted to yield an adequately controlled oxidation process inaccordance with the aspects of the invention described herein. Oneeffective example includes forming a plasma by applying an AC voltageacross a deposition substrate and a counter electrode while flowingoxygen into a vacuum chamber held at a pressure of about 2 to about 50microns of Hg. A triode arrangement may also be useful in producing anoxygen plasma with suitable oxidation properties.

Implanting of oxygen ions can also occur from a source other than anoxygen plasma. A low energy ion beam can provide a flux of a desiredionic oxygen species. An alternative oxidation method includes using anozone source to provide oxygen neutrals. The ozone may decompose to formmolecular and nascent or atomic oxygen. Atomic oxygen is very smallcompared to molecular oxygen and can diffuse more rapidly through agrowing oxide surface layer to reach unreacted material beneath, formingan oxide at an enhanced, but quite controllable, rate. As examples,silicon and lead can significantly oxidize at relatively lowtemperatures in ozone.

The specific thickness of the outer portion oxidized to retardinterdiffusion and/or implanted with oxygen ions will depend on avariety of factors. Greater differences between metals in chemicalaffinity for oxygen, higher process temperatures used to convert to theperovskite-type crystalline structure, greater thicknesses of theoverall material, etc. might motivate a desire for increased thicknessof the outer portion to retard interdiffusion. Typically, exposure to anoxygen plasma and/or implanting oxygen ions can occur at temperaturessufficiently low that interdiffusion of metals in the material is not ofsignificant concern. Concern becomes significant when interdiffusionreaches a level hampering the ability to obtain stoichiometricperovskite-type crystalline structures.

Additional oxidation of the material after retarding interdiffusion maybe desirable to increase the amount of material that can be converted toa perovskite-type crystalline structure. Accordingly, oxidizing thematerial described above can include oxidizing only a first portion ofthe material and the method can further include, separately from theconverting, oxidizing a second portion of the material beneath the firstportion. Further, another aspect of the invention includes forming analloy material containing at least two metals over a substrate andretarding interdiffusion of the at least two metals. The method canadditionally include oxidizing the alloy material after the retardinginterdiffusion. The alloy film can be annealed prior to oxidation inorder to change the initial film morphology and stress if desired. Atleast a portion of the oxidized alloy material can be converted to aperovskite-type crystalline structure.

As described herein, reaction with carbon and nitrogen can producecarbide and nitride impurities that interfere with perovskiteconversion. One option to prevent carbon and nitrogen incorporationincludes performing each part of the method in situ, that is, in thesame process chamber. Alternatively, the various aspects of the methodcan occur in a processing device having one or more chambers that may beused to complete the method without exposure to ambient conditions. Forexample, forming the material can occur in the processing device and theoxidizing can include substantially complete oxidation of the materialalso in the processing device prior to removal from the processingdevice. “Substantially complete” oxidation refers to providing asufficient amount of oxygen to achieve a desired perovskite-typecrystalline structure. Such could be accomplished by oxidizing the outerportion and implanting oxygen ions in situ with the forming thematerial. Next, an inner portion of the material can be oxidized eitherin situ or in a chamber of the processing device without ambientexposure to substantially complete oxidation of the material. Also,oxidizing and implanting could occur in a different chamber of theprocessing device than the forming the material, but without ambientexposure. Notably, the aspects of the invention described herein with avariety of oxidation options provides simple mechanisms for fine tuningmaterial compositions to achieve suitable stoichiometry prior toperovskite conversion.

The oxidizing the material and converting the material can occur indifferent process chambers. The different process chambers might becomprised by a multi-chamber processing device. Also, the oxidizingmight include substantially complete oxidation, reducing a concern fornitride or carbide formation. However, the method can instead or furtherinclude forming a passivation layer to carbon and nitrogen over thematerial. Oxides of amorphous silicon, aluminum, or alloys thereof aresuitable examples of passivation materials, although other suitablematerials likely exist. A passivation material might be deposited in aprimarily unoxidized state with a sufficient amount of oxidationoccurring as a result of ambient oxygen exposure to accomplishsufficient passivation. After passivation, the underlying material,perhaps partially oxidized material, can be ambient exposed withoutsignificant concern for nitride or carbide formation. Substantiallycomplete oxidation can occur later after forming the passivation layer.As one example, forming the passivation layer can occur in situ withforming the material over the substrate and/or in situ with oxidizingthe material incompletely or substantially completely.

A possibility exists that components of a passivation layer mightdiffuse into underlying material during subsequent higher temperatureprocessing. An extremely thin film can be used as a passivation layer toprevent reaction with impurities during ambient exposure. Thickness ispreferably from about 0.5 to about 2 nanometers (nm) but can be higher.Accordingly, oxidizing a passivation film to retard diffusion intounderlying material might be easily done. Such oxidation can occur atless than about 200 C. One example includes using a microwave dischargeof an oxygen plasma to quickly oxidize the extremely thin film. Otheroxidization methods may be additionally suitable.

The method can further include oxidizing a second portion of thematerial after oxidizing the passivation layer. Oxidizing the secondportion can accomplish substantially complete oxidation of the material.Also, oxidizing the second portion can occur in situ with oxidizing thepassivation layer. Appropriate oxidized materials described above can beconverted to a perovskite-type crystalline structure by heating. Theheating can occur in situ, in a multi-chamber processing device, or in aseparate chamber after ambient exposure. Preferably, providing apassivation layer precedes ambient exposure. Heating can includereaching a maximum temperature no more than about one-half of a meltingpoint temperature of the perovskite-type material. Preferably, heatingincludes reaching a maximum temperature of no more than about one-thirdof the melting point temperature.

The various oxidations described above can generally be accomplished attemperatures of less than about 600 C., especially when using amicrowave discharge of an oxygen plasma. The lower temperatureoxidations minimize degradation of integrated circuit components thatmight exist in association with the perovskite-type material. Subsequentperovskite conversion can typically occur at about 700 C. or in keepingwith melting point temperatures often associated with perovskite-typematerial. Conversion can occur by controlling temperature at 700 C., oranother suitable temperature, for an entirety of a selected duration.Also, conversion can occur by using various heating and cooling steps tocontrol thermal budget. Some perovskite-type materials might convert attemperatures less than 700 C. Also, conversion of only a portion of theoxidized material might be suitable to obtain the desired material.

Conversion of the oxidized material to a perovskite-type crystallinestructure can occur in an atmosphere purged of oxygen. Purging of oxygencan occur in keeping with the knowledge of those of ordinary skill inthe art. Since the conversion can occur at higher temperatures thanoxidation, purging oxygen aids in preventing oxidation of integratedcircuit components, particularly those containing silicon, that might beassociated with the perovskite-type material. However, molecular oxygencan be added during conversion rather than using a purged chamber tofine tune stoichiometry.

In one application, the substrate can include a capacitor electrode andthe converted, oxidized material can include a capacitor dielectriclayer. The substrate might also include a semiconductor substrate. Inthe context of this document, the term “semiconductor substrate” or“semiconductive substrate” is defined to mean any constructioncomprising semiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials thereon), and semiconductivematerial layers (either alone or in assemblies comprising othermaterials). The term “substrate” refers to any supporting structure,including, but not limited to, the semiconductive substrates describedabove. A suitable dielectric layer might be obtained with only partialconversion to a perovskite-type crystalline structure. Potentially, thecrystallized perovskite can be in a monocrystalline form, but is morelikely microcrystalline.

In a circumstance where a passivation layer is formed and oxidized, thepassivation layer can provide an additional capacitor dielectric layer.A passivation layer oxidized to SiO₂ or Al₂ 0 ₃ might slightly reducethe overall storage capacity of a capacitor given a likely lowerdielectric constant. However, given the extremely high K of theperovskite-type material, the slight effect of the additional dielectricmay be acceptable. Further, given the different chemical and physicalcharacteristics of the underlying perovskite-type material, the oxidizedpassivation layer might reduce defect densities for the doubledielectric. If desired, the passivation layer or oxidized passivationlayer can be removed at an appropriate point in processing. Selectivereactive ion etching might easily remove SiO₂ in preference to a typicalunderlying perovskite-type material.

According to one aspect of the invention, a capacitor dielectric formingmethod includes forming an alloy layer comprising at least two metalsover a capacitor electrode, oxidizing the alloy layer, and convertingthe alloy layer to form a capacitor dielectric layer comprising aperovskite-type crystalline structure. Having the metals in solidsolution as an alloy and maintain the metal distribution throughoutoxidation can facilitate later conversion to substantiallystoichiometric perovskite-type crystalline structure. The variousmethods described above are accordingly applicable to converting analloy layer.

FIG. 1 shows an inner electrode 4 formed over a substrate 2. Even thoughelectrode 4 is shown as planar, the capacitor dielectrics discussedherein can be adapted to any variety of capacitor structures. Innerelectrode 4 can include metals such as Ru, Ir, and Pt as well as theirconductive oxides, highly doped silicon, and additional materialsconsidered suitable by those of ordinary skill.

FIG. 2 shows an alloy 6 containing at least two metals formed over innerelectrode 4. Alloy 6 can be oxidized and converted to a perovskite-typecrystalline structure providing a dielectric 8 as shown in FIG. 3. Alloy6 can be formed having a thickness of from about 1 nm to about 500 nm,but preferably from about 3 to about 30 nm. Depending on the particularmetals selected for the alloy and the target perovskite composition, thethickness of alloy 6 can increase during oxidation. About 50% growth isoften expected though not shown in the Figures. Since thin dielectriclayers are often preferred, dielectric 8 can have a thickness less thanabout 100 Angstroms, but preferably less than about 50 Angstromsassuming sufficient dielectric properties. Alloy 6 can be formed by avariety of methods including physical vapor deposition, sputtering, etc.from a single source or multiple sources.

FIG. 4 shows an outer electrode 10 formed over dielectric 8 providing acapacitor construction 12. Although not shown in FIG. 4, a variety ofadditional layers can be formed between one or more of substrate 2 andthe various layers shown. The purpose of additional layers might be toimprove on the basic capacitor construction 12 in accordance with theknowledge of those skilled in the art.

FIG. 5 shows alternate processing subsequent to that shown in FIG. 2wherein outer portion 16 of alloy 6 is oxidized but inner portion 14remains largely as shown in FIG. 2. Outer portion 16 can have athickness of from about 0.5 to about 2 nm and sufficiently retardinterdiffusion in an alloy film of about 3 to about 30 nm. However, inkeeping with principles described herein, outer portion 16 might be morethick.

FIG. 6 shows passivation 18 formed over outer portion 16 to reducematerial degradation during ambient exposure. Passivation 18 can evenallow storage of the construction shown in FIG. 6 under low relativehumidity conditions for further processing at a later time. Notably,passivation 18 is shown without hatching indicating a non-metallicmaterial. However, passivation 18 can be a metallic material, such asAl, or a nonmetal, such as Si. In the context of the present document,“metals” refers to the elements of Groups IA, IIA, and IB to VIIIB ofthe periodic table of the elements along with the portions of GroupsIIIA to VIA designated as metals in the periodic table, namely, Al, Ga,In, TI, Ge, Sn, Pb, Sb, Bi, and Po. “Non-metals” refers to the remainingelements of the periodic table.

FIG. 7 shows passivation 18 oxidized to an outer dielectric 20 and innerportion 14 along with outer portion 16 oxidized and converted todielectric 8 having a perovskite-type crystalline structure. An outerelectrode 10 is formed over outer dielectric 20 to produce a capacitorconstruction 24.

According to another aspect of the invention, a capacitor dielectricforming method includes vacuum depositing an alloy layer containing atleast two metals exhibiting a substantial difference in chemicalaffinity for oxygen. The vacuum depositing can occur over a capacitorelectrode in a processing device having one or more chambers. The methodincludes oxidizing a first portion of the deposited alloy layer with anoxygen plasma and implanting oxygen ions into the deposited alloy layer.The oxidizing and implanting can occur at a first temperature in theprocessing device after the vacuum depositing, but before removal offrom the processing device. The method also includes oxidizing a secondportion of the deposited alloy layer. The method further includesseparately from oxidizing the first and second portions, heating theoxidized alloy layer and converting at least a portion of the oxidizedalloy layer to a perovskite-type crystalline structure to form acapacitor dielectric layer. During conversion, a second temperature canbe reached greater than the first temperature but no more than aboutone-half of a melting point temperature of the layer portion having theperovskite-type structure. As an option, the method may further includevacuum depositing a passivation layer to carbon and nitrogen reactionover the alloy layer. The passivation layer can be oxidized to anadditional dielectric layer before oxidizing the second portion of thedeposited alloy layer. Additionally, oxidizing the second portion canoccur in situ with oxidizing the passivation layer.

The methods described herein are not limited to formation of a singlelayer having a perovskite-type crystalline structure or a singlecomposition for the perovskite-type crystalline structure. Differentstarting materials can be provided or different oxidation processing canoccur to yield multiple layers of perovskite-type material having thesame or different composition. Accordingly, a capacitor dielectricforming method includes forming a first alloy layer containing at leasttwo metals over a capacitor electrode and forming a second alloy layercomprising at least two metals over the first alloy layer. The methodincludes oxidizing the first alloy layer and oxidizing the second alloylayer. The method also includes processing the first alloy layer to forma first capacitor dielectric layer having a perovskite-type crystallinestructure and processing the second alloy layer to form a secondcapacitor dielectric layer having a perovskite-layer crystallinestructure. The method may include completion of processing the firstalloy layer before forming the second alloy layer. The method mayinstead include oxidizing the first and second alloy layers together.The method can further include processing the first and second alloylayers together. Accordingly, FIG. 8 shows a capacitor construction 30where dielectric 8 is replaced by a first dielectric 26 and a seconddielectric 28. Outer dielectric 20 such as shown in FIG. 7 is over firstand second dielectrics 26, 28.

As indicated herein, the aspects of the invention are extendable toforming other than perovskite-type materials. Specifically, a capacitordielectric forming method can include vacuum depositing an alloy layercontaining at least two metals exhibiting a substantial difference inchemical affinity for oxygen. The vacuum depositing can occur over acapacitor electrode. The method includes oxidizing substantially all ofthe deposited alloy layer using at least an oxygen plasma andimplantation of oxygen ions into the deposited alloy layer. Theoxidizing and the implanting can occur at a first temperature in situwith the depositing. The method further includes, separately from theoxidizing, heating the oxidized alloy layer and converting substantiallyall of the oxidized alloy layer to a crystalline structure to form acapacitor dielectric layer. A second temperature can be reached greaterthan the first temperature at about one-third of a melting pointtemperature of the layer having the crystalline structure.

A further alternative aspect of the invention provides a capacitordielectric forming method including vacuum depositing as described inthe immediately preceding paragraph. The method includes oxidizing afirst portion of the deposited alloy layer with an oxygen plasma andimplanting oxygen ions into the deposited alloy layer. A passivationlayer can be vacuum deposited over the oxidized alloy layer in situ withoxidizing the first portion. The passivation layer can be oxidized toform an outer capacitor dielectric layer. A second portion of thedeposited alloy layer can be oxidized in situ with oxidizing thepassivation layer. Separately from oxidizing the first and secondportions, the oxidized alloy layer can be heated and converted, at leastin part, to a crystalline structure to form an inner capacitordielectric layer.

A variety of capacitor constructions can result from the various methodsaccording to the aspects of the invention herein. Accordingly, oneaspect provides a capacitor construction including an inner electrode,an inner dielectric layer over the inner electrode, an outer dielectriclayer over the inner dielectric layer, and an outer electrode over theouter dielectric layer. The inner dielectric layer can include anoxidized alloy of at least two metals in a perovskite-type crystallinestructure. The outer dielectric layer can include an oxide of a materialwherein the material exhibits passivation against carbon and nitrogenreaction. The capacitor construction can further include a middledielectric layer between the inner and outer dielectric layers. Themiddle dielectric layer can include an oxidized alloy of at least twometals in a perovskite-type crystalline structure.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A capacitor construction comprising: an innerelectrode; an inner dielectric layer over the inner electrode, the innerdielectric layer comprising an oxidized alloy of at least two metals ina perovskite-type crystalline structure; an outer dielectric layer overthe inner dielectric layer, the outer dielectric layer comprising anoxide of a material and the material exhibiting passivation againstcarbon and nitrogen reaction; and an outer electrode over the outerdielectric layer.
 2. The capacitor construction of claim 1, wherein theouter dielectric layer is on and in contact with the inner dielectriclayer.
 3. The capacitor construction of claim 1 further comprising amiddle dielectric layer between the inner and outer dielectric layers,the middle dielectric layer comprising an oxidized alloy of at least twometals in a perovskite-type crystalline structure.
 4. The capacitorconstruction of claim 1 produced by a process comprising: vacuumdepositing an inner layer comprising the alloy of at least two metals,the vacuum depositing occurring over the inner electrode in a processingdevice comprising one or more chambers; oxidizing a first portion of thedeposited inner alloy layer with an oxygen plasma and implanting oxygenions into the deposited inner alloy layer, the oxidizing and theimplanting occurring at a first temperature in the processing deviceafter the vacuum depositing but before removal from the processingdevice; vacuum depositing a passivation layer to carbon and nitrogenreaction over the inner alloy layer; oxidizing the passivation layer toform the outer dielectric layer; oxidizing a second portion of thedeposited inner alloy layer; and separately from the oxidizing the firstand second portions, heating the oxidized inner alloy layer, convertingat least a portion of the oxidized inner alloy layer to aperovskite-type crystalline structure to form the inner dielectriclayer, and reaching a second temperature greater than the firsttemperature but no more than about one-half of a melting pointtemperature of the layer portion having the perovskite-type structure.5. The capacitor construction of claim 1 wherein the outer dielectriclayer has a thickness of from about 0.5 to about 2 nanometers.
 6. Thecapacitor construction of claim 1 wherein at least two of the metalsexhibit a substantial difference in chemical affinity for oxygen.
 7. Thecapacitor construction of claim 1 wherein at least one of the at leasttwo metals is selected from the group consisting of Ti, alkaline earthmetals, and lanthanide metals.
 8. The capacitor construction of claim 1wherein the perovskite-type crystalline structure comprises PbTiO₃ orPbZr_(y)Ti_(1-y)O₃.
 9. The capacitor construction of claim 1 wherein thematerial comprises amorphous silicon, aluminum, or alloys thereof. 10.The capacitor construction of claim 9 wherein the oxide of the materialcomprises Al₂O₃.
 11. The capacitor construction of claim 9, wherein theoxide of the material comprises SiO₂.
 12. A capacitor intermediateconstruction comprising: an inner electrode; an inner dielectric layerover the inner electrode, the inner dielectric layer comprising anoxidized alloy of at least two metals in a perovskite-type crystallinestructure; and a passivation layer over the inner dielectric layer, thepassivation layer exhibiting passivation against carbon and nitrogenreaction with the inner dielectric layer.
 13. The intermediateconstruction of claim 12 wherein the passivation layer is on and incontact with the inner dielectric layer.
 14. The intermediateconstruction of claim 12 further comprising a middle dielectric layerbetween the inner dielectric layer and the passivation layer, the middledielectric layer comprising an oxidized alloy of at least two metals ina perovskite-type crystalline structure.
 15. The intermediateconstruction of claim 12, wherein the passivation layer has a thicknessof from about 0.5 to about 2 nanometers.
 16. The intermediateconstruction of claim 12 wherein at least two of the metals exhibit asubstantial difference in chemical affinity for oxygen.
 17. Theintermediate construction of claim 12 wherein at least one of the atleast two metals is selected from the group consisting of Ti, alkalineearth metals, and lanthanide metals.
 18. The intermediate constructionof wherein the perovskite-type crystalline structure comprises PbTiO₃orPbZr_(y)Ti_(1-y)O₃.
 19. The intermediate construction of claim 12wherein the passivation layer comprises amorphous silicon, aluminum, oralloys thereof.
 20. The intermediate construction of claim 19 whereinthe passivation layer comprises Al₂O₃.
 21. The intermediate constructionof claim 19, wherein the passivation layer comprises SiO₂.